U.S. patent application number 12/223011 was filed with the patent office on 2009-11-05 for display device and electronic device.
This patent application is currently assigned to Sony Corporation. Invention is credited to Daisuke Ito, Yoshitoshi Kida, Masaki Murase, Yoshiharu Nakajima, Masaaki Tonogai.
Application Number | 20090273593 12/223011 |
Document ID | / |
Family ID | 38287695 |
Filed Date | 2009-11-05 |
United States Patent
Application |
20090273593 |
Kind Code |
A1 |
Tonogai; Masaaki ; et
al. |
November 5, 2009 |
Display Device and Electronic Device
Abstract
A display device of a type capable of narrowing the pitch,
realizing narrowing of the frame, and further lowering the power
consumption and an electronic device using the device, wherein two
horizontal drive circuits 13U and 13D employ an RGB selector scheme
by storing three digital data in sampling and latch circuits,
performing conversion processing to analog data three times by a
common digital-to-analog conversion circuit during one horizontal
period (H), selecting three analog data in the horizontal period in
a time division manner, and outputting the same to data lines
(signal lines).
Inventors: |
Tonogai; Masaaki; (Tokyo,
JP) ; Nakajima; Yoshiharu; (Kanagawa, JP) ;
Kida; Yoshitoshi; (Kanagawa, JP) ; Murase;
Masaki; (Kanagawa, JP) ; Ito; Daisuke; (Tokyo,
JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING, 1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Assignee: |
Sony Corporation
Tokyo
JP
|
Family ID: |
38287695 |
Appl. No.: |
12/223011 |
Filed: |
January 19, 2007 |
PCT Filed: |
January 19, 2007 |
PCT NO: |
PCT/JP2007/050792 |
371 Date: |
June 8, 2009 |
Current U.S.
Class: |
345/214 ;
345/55 |
Current CPC
Class: |
G09G 3/3688 20130101;
G09G 2310/027 20130101; G09G 2310/0297 20130101; G09G 2310/0294
20130101; G09G 2330/021 20130101 |
Class at
Publication: |
345/214 ;
345/55 |
International
Class: |
G06F 3/038 20060101
G06F003/038; G09G 3/20 20060101 G09G003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2006 |
JP |
2006-013127 |
Claims
1. A display device, comprising: a display portion having pixels
arranged in a matrix, a vertical drive circuit selecting pixels of
the display portion in units of rows, and a horizontal drive
circuit receiving as input first, second, and third digital image
data, converting the digital image data to analog image signals,
and supplying the signals to data lines to which pixels of a row
selected by the vertical drive circuit are connected, wherein: the
horizontal drive circuit includes a first latch system including a
first sampling and latch circuit sampling and latching the first
digital image data, a second sampling and latch circuit sampling
and latching the second digital image data, and a first latch
circuit latching the latched data of the first and second sampling
and latch circuits again, a second latch system including a third
sampling and latch circuit sampling and latching the third digital
image data, a digital-to-analog conversion circuit (DAC) converting
the first, second, and third digital image data latched by the
first latch system and the second latch system to analog data
during one horizontal period, and a line selector selecting the
first, second, and third analog image data converted to analog data
by the DAC within a predetermined period in a time division manner
and outputting these analog image data to the data lines.
2. A display device as set forth in claim 1, wherein the first
latch system has a second latch circuit latching the data latched
by the first latch circuit, the second latch system has a third
latch circuit latching the data latched by the third sampling and
latch circuit again, and the device further comprises a selection
switch selectively outputting the digital image data latched by the
second latch circuit and the third latch circuit to the DAC.
3. A display device as set forth in claim 2, wherein in the
horizontal drive circuit, the first and second sampling and latch
circuits are cascade connected, the horizontal drive circuit
includes the first latch circuit and second latch circuit cascade
connected with respect to the output of the second sampling and
latch circuit, and the first and second sampling and latch circuits
store first digital image data and second digital image data by the
same sampling pulse, transfer the second digital image data of the
second sampling and latch circuit through the first latch circuit
to the second latch circuit, and next transfer the first digital
image data of the first sampling and latch circuit through the
second sampling and latch circuit to the second latch circuit.
4. A display device as set forth in claim 1, wherein: the
horizontal drive circuit does not perform transfer processing of
the third digital image data during a term where data of one line
in the horizontal direction is stored.
5. A display device as set forth in claim 3, wherein: the
horizontal drive circuit does not perform transfer processing of
the third digital image data during a term where data of one line
in the horizontal direction is stored.
6. A display device as set forth in claim 1, wherein the third
digital image data is data having an intermediate wavelength band
among the three digital image data.
7. An electronic device comprising a display device, wherein the
display device comprises a display portion having pixels arranged
in a matrix, a vertical drive circuit selecting pixels of the
display portion in units of rows, and a horizontal drive circuit
receiving as input first, second, and third digital image data,
converting the digital image data to analog image signals, and
supplying the signals to data lines to which pixels of the row
selected by the vertical drive circuit are connected, in which the
horizontal drive circuit includes a first latch system including a
first sampling and latch circuit sampling and latching the first
digital image data, a second sampling and latch circuit sampling
and latching the second digital image data, and a first latch
circuit latching the latched data of the first and second sampling
and latch circuits again, a second latch system including a third
sampling and latch circuit sampling and latching the third digital
image data, a digital-to-analog conversion circuit (DAC) converting
the first, second, and third digital image data latched by the
first latch system and the second latch system to analog data
during one horizontal period, and a line selector selecting the
first, second, and third analog image data converted to analog data
by the DAC within a predetermined period in a time division manner
and outputting these analog image data to the data lines.
8. An electronic device as set forth in claim 7, wherein: the first
latch system has a second latch circuit latching the data latched
by the first latch circuit, the second latch system has a third
latch circuit latching the data latched by the third sampling and
latch circuit again, and the device further comprises a selection
switch selectively outputting digital image data latched by the
second latch circuit and the third latch circuit to the DAC.
9. An electronic device as set forth in claim 8, wherein: in the
horizontal drive circuit, the first and second sampling and latch
circuits are cascade connected, the horizontal drive circuit
includes the first latch circuit and the second latch circuit
cascade connected with respect to the output of the second sampling
and latch circuit, the first and second sampling and latch circuits
store the first digital image data and the second digital image
data by the same sampling pulse, the second digital image data of
the second sampling and latch circuit is transferred through the
first latch circuit to the second latch circuit, and next, the
first digital image data of the first sampling and latch circuit is
transferred through the second sampling and latch circuit to the
second latch circuit.
10. An electronic device as set forth in claim 7, wherein: the
horizontal drive circuit does not perform transfer processing of
the third digital image data during the period where data of one
line in the horizontal direction is stored.
11. An electronic device as set forth in claim 9, wherein: the
horizontal drive circuit does not perform transfer processing of
the third digital image data during the period where data of one
line in the horizontal direction is stored.
12. An electronic device as set forth in claim 7, wherein: wherein
the third digital image data is data having an intermediate
wavelength band among the three digital image data.
Description
TECHNICAL FIELD
[0001] The present invention relates to a liquid crystal display
device or other active matrix type display device and an electronic
device using the device.
BACKGROUND ART
[0002] In recent years, mobile phones, PDA (personal digital
assistants), and other portable terminals have remarkably spread.
As one of factors of the rapid spread of these portable terminals,
the liquid crystal display devices mounted as their output displays
can be mentioned. The reason is that liquid crystal display devices
have the feature that they do not in principle require electric
power for being driven and therefore are low power consumption
display devices.
[0003] In recent years, in active matrix type display devices using
polysilicon TFTs (thin film transistors) as switching elements of
pixels, a tendency is to integrally form the digital interface
drive circuit on the same substrate as the display area where the
pixels are arranged in a matrix.
[0004] In such an integral drive circuit type display device, a
horizontal drive system and a vertical drive system are arranged at
a periphery (frame) of an effective display portion. These drive
systems are integrally formed on the same substrate together with
the pixel area using low temperature polysilicon TFTs.
[0005] FIG. 1 is a diagram showing the schematic configuration of a
general integral drive circuit type display device (see for
example, Patent Document 1).
[0006] This liquid crystal display device, as shown in FIG. 1, is
formed by a transparent insulating substrate, for example a glass
substrate 1, on which an effective display portion 2 having a
plurality of pixels including liquid crystal cells arranged in a
matrix, a pair of horizontal drive circuits (H drivers) 3U and 3D
arranged above and below the effective display portion 2 in FIG. 1,
a vertical drive circuit (V driver) 4 arranged at a side portion of
the effective display portion 2 in FIG. 1, one reference voltage
generation circuit (REF.DRV) 5 for generating a plurality of
reference voltages, a data processing circuit (DATAPRC) 6, etc. are
integrated.
[0007] In this way, the integral drive circuit type display device
of FIG. 1 has two horizontal drive circuits 3U and 3D arranged on
the two sides (above and below in FIG. 1) of the effective pixel
portion 2. This is in order to separately drive the data lines
divided in odd number lines and even number lines.
[0008] FIG. 2 is a block diagram showing an example of the
configuration of the horizontal drive circuits 3U and 3D for
separately driving odd number lines and even number lines.
[0009] As shown in FIG. 2, the horizontal drive circuit 3U for
driving the odd number lines and the horizontal drive circuit 3D
for driving the even number lines have the same configuration.
[0010] Specifically, they have shift register (HSR) groups 3HSRU
and 3HSRD for sequentially outputting shift pulses (sampling
pulses) from transfer stages in synchronization with horizontal
transfer clocks HCK (not shown), sampling and latch circuit groups
3SMPLU and 3SMPLD for sequentially sampling and latching digital
image data by sampling pulses given from shift registers 31U and
31D, linear sequencing latch circuit groups 3LTCU and 3LTCD for
linearly sequencing latch data of sampling and latch circuits 33U
and 33D, and digital/analog conversion circuit (DAC) groups 3DACU
and 3DACD for converting digital image data linearly sequenced at
the linear sequencing latch circuits 33U and 33D to analog image
signals.
[0011] Note that, usually, at input stages of DAC 34U and DAC 34D,
level shift circuits are arranged, and level up data are input to
the DACs 34.
[0012] Patent Document 1: Japanese Patent Publication (A) No.
2002-175033
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0013] However, in the horizontal drive circuit of FIG. 2 explained
above, one set includes a sampling and latch circuit 32, a linearly
sequencing latch circuit 33, and a DAC 34 and one set is needed for
each data line, therefore the lateral width permitted in terms of
layout is small. For this reason, reduction of the pitch is
difficult. Further, the number of required circuits is large,
therefore there are the disadvantages that the frame becomes large
and the power consumption is big.
[0014] In the case of the horizontal drive circuit of FIG. 2, three
sampling and latch circuits sampling serial-to-parallel converted R
(red), G (green), and B (blue) data are needed. However, it is
difficult to cope with demands for narrowing the pitch and
narrowing the frame by this.
[0015] In order to overcome this, extension of the layout so-called
in the vertical direction can be considered. However, the layout
area abruptly increases by this and it is difficult to realize
frame narrowing.
[0016] The present invention provides a display device of a type
capable of narrowing the pitch, able to realize frame narrowing,
and capable of further lowering the power consumption and an
electronic device using the device.
MEANS FOR SOLVING THE PROBLEMS
[0017] To attain the above object, a display device of a first
aspect of the present invention has a display portion having pixels
arranged in a matrix, a vertical drive circuit selecting pixels of
the display portion in units of rows, and a horizontal drive
circuit receiving as input first, second, and third digital image
data, converting the digital image data to analog image signals,
and supplying the signals to data lines to which pixels of a row
selected by the vertical drive circuit are connected, wherein the
horizontal drive circuit includes a first latch system including a
first sampling and latch circuit sampling and latching the first
digital image data, a second sampling and latch circuit sampling
and latching the second digital image data, and a first latch
circuit latching the latched data of the first and second sampling
and latch circuits again, a second latch system including a third
sampling and latch circuit sampling and latching the third digital
image data, a digital-to-analog conversion circuit (DAC) converting
the first, second, and third digital image data latched by the
first latch system and the second latch system to analog data
during one horizontal period, and a line selector selecting the
first, second, and third analog image data converted to analog data
by the DAC within a predetermined period in a time division manner
and outputting these analog image data to the data lines.
[0018] Preferably, the first latch system has a second latch
circuit latching the data latched by the first latch circuit, the
second latch system has a third latch circuit latching the data
latched by the third sampling and latch circuit again, and the
device further has a selection switch selectively outputting the
digital image data latched by the second latch circuit and the
third latch circuit to the DAC.
[0019] Preferably, in the horizontal drive circuit, the first and
second sampling and latch circuits are cascade connected, the
horizontal drive circuit includes the first latch circuit and
second latch circuit cascade connected with respect to the output
of the second sampling and latch circuit, and the first and second
sampling and latch circuits store first digital image data and
second digital image data by the same sampling pulse, transfer the
second digital image data of the second sampling and latch circuit
through the first latch circuit to the second latch circuit, and
next transfer the first digital image data of the first sampling
and latch circuit through the second sampling and latch circuit to
the second latch circuit.
[0020] Preferably, the third digital image data is data having an
intermediate wavelength band among the three digital image
data.
[0021] A second aspect of the present invention is an electronic
device has a display device, wherein the display device has a
display portion having pixels arranged in a matrix, a vertical
drive circuit selecting pixels of the display portion in units of
rows, and a horizontal drive circuit receiving as input first,
second, and third digital image data, converting the digital image
data to analog image signals, and supplying the signals to data
lines to which pixels of the row selected by the vertical drive
circuit are connected, in which the horizontal drive circuit
includes a first latch system including a first sampling and latch
circuit sampling and latching the first digital image data, a
second sampling and latch circuit sampling and latching the second
digital image data, and a first latch circuit latching the latched
data of the first and second sampling and latch circuits again, a
second latch system including a third sampling and latch circuit
sampling and latching the third digital image data, a
digital-to-analog conversion circuit (DAC) converting the first,
second, and third digital image data latched by the first latch
system and the second latch system to analog data during one
horizontal period, and a line selector selecting the first, second,
and third analog image data converted to analog data by the DAC
within a predetermined period in a time division manner and
outputting these analog image data to the data lines.
EFFECTS OF THE INVENTION
[0022] According to the present invention, an integral drive
circuit type display device capable of handling higher definitions
with a narrow frame and having a low power consumption can be
realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a diagram schematically showing the configuration
of a general integral drive circuit type display device.
[0024] FIG. 2 is a block diagram showing an example of the
configurations of the horizontal drive circuits of FIG. 1
separately driving odd number lines and even number lines.
[0025] FIG. 3 is a diagram showing the layout configuration of an
integral drive circuit type display device according to a first
embodiment of the present invention.
[0026] FIG. 4 is a system block diagram showing circuit functions
of the integral drive circuit type display device according to the
first embodiment of the present invention.
[0027] FIG. 5 is a circuit diagram showing an example of the
configuration of an effective display portion of a liquid crystal
display device.
[0028] FIG. 6 is a block diagram showing an example of the basic
configurations of first and second horizontal drive circuits of the
present embodiment.
[0029] FIG. 7 is a circuit diagram showing a concrete configuration
of a first latch system of the horizontal drive circuit according
to a second embodiment.
[0030] FIG. 8 is a circuit diagram showing a concrete configuration
of a second latch system of the horizontal drive circuit according
to the second embodiment.
[0031] FIG. 9 is a diagram showing relationships of up/down
directional frame sizes and potential higher definition regions of
an existing system and the system of the present invention when
realizing the device of FIG. 3 and FIG. 4 by QVGA.
[0032] FIG. 10 is a diagram showing a layout configuration of an
integral drive circuit type display device according to a third
embodiment of the present invention.
[0033] FIG. 11 is a system block diagram showing the circuit
functions of the integral drive circuit type display device
according to the third embodiment of the present invention.
[0034] FIG. 12 is a diagram of an outer appearance schematically
showing the configuration of a mobile phone as a mobile terminal
device according to an embodiment of the present invention.
EXPLANATION OF REFERENCE
[0035] 10, 10A . . . liquid crystal display devices, 11 . . . glass
substrate, 12 . . . effective display portion, 13 . . . horizontal
drive circuit, 13U . . . first horizontal drive circuit, 13D . . .
second horizontal drive circuit, 13SMPL . . . sampling and latch
circuit groups, 131 . . . first sampling and latch circuit, 132 . .
. second sampling and latch circuit, 133 . . . third sampling and
latch circuit, 134 . . . first latch circuit, 135 . . . second
latch circuit, 136 . . . third latch circuit, 137 . . . first latch
system, 138 . . . second latch system, 13OSEL . . . latch output
selection switch, 13DAC . . . digital-to-analog conversion circuit,
13ABUD . . . analog buffer, 13LSEL . . . line selector, 14 . . .
vertical drive circuit, 15 . . . data processing circuit, 16 . . .
power supply circuit, 17 . . . interface circuit, and 18 . . .
timing generator.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] Below, embodiments of the present invention will be
explained in detail with reference to the drawings.
First Embodiment
[0037] FIG. 3 and FIG. 4 are diagrams of configurations
schematically showing an example of the configuration of an
integral drive circuit type display device according to a first
embodiment of the present invention, in which FIG. 3 is a diagram
showing a layout configuration of the integral drive circuit type
display device according to the first embodiment, and FIG. 4 is a
system block diagram showing circuit functions of the integral
drive circuit type display device according to the first embodiment
of the present invention.
[0038] Here, for example, an explanation will be given by taking as
an example a case where the present invention is applied to an
active matrix type liquid crystal display device using liquid
crystal cells as electro-optic elements of the pixels.
[0039] This liquid crystal display device 10, as shown in FIG. 3,
is formed by a transparent insulating substrate, for example, a
glass substrate 11, on which an effective display portion (ACDSP)
12 having a plurality of pixels including liquid crystal cells
arranged in a matrix, a pair of first and second horizontal drive
circuits (H drivers, HDRV) 13U and 13D arranged above and below the
effective display portion 12 in FIG. 3, a vertical drive circuit (V
driver, VDRV) 14 arranged at the side portion of the effective
display portion 12 in FIG. 3, a data processing circuit (DATAPRC)
15, a power supply circuit (DC-DC) 16 formed by a DC-DC converter,
an interface circuit (I/F) 17, a timing generator (TG) 18, and a
reference voltage drive circuit (REFDRV) 19 supplying a plurality
of drive reference voltages to the horizontal drive circuits 13U,
13D etc., and so on are integrated.
[0040] Further, an input pad 20 for data etc. is formed in an edge
portion in the vicinity of the position of arrangement of the
second horizontal drive circuit 13D of the glass substrate 11.
[0041] The glass substrate 11 is constituted by a first substrate
having a plurality of pixel circuits including active elements (for
example transistors) arranged in a matrix and a second substrate
arranged facing this first substrate with a predetermined
clearance. Further, a liquid crystal is sealed between these first
and second substrates.
[0042] Circuit groups formed on the insulating substrate are formed
by a low temperature polycrystalline silicon TFT process. Namely,
in this integral drive circuit type display device 10, the
horizontal drive systems and vertical drive system are arranged at
the periphery (frame) of the effective display portion 12. These
drive systems are integrally formed on the same substrate together
with the pixel area portion by using polycrystalline silicon
TFTs.
[0043] The integral drive circuit type display device 10 of the
present embodiment arranges two horizontal drive circuits 13U and
13D on the two sides of (above and below in FIG. 3) the effective
pixel portion 12. This arrangement is made for driving data lines
while dividing these to odd number lines and even number lines.
[0044] The two horizontal drive circuits 13U and 13D employ an RGB
selector scheme by storing three digital data in sampling and latch
circuits, performing the conversion processing to analog data three
times by the common digital-to-analog conversion circuit during one
horizontal period (H), selecting three analog data in the
horizontal period in a time division manner, and outputting the
same to data lines (signal lines).
[0045] In the present embodiment, among the three digital image
data R, G, and B, the digital R data will be explained as first
digital data, the digital B data will be explained as second
digital data, and the digital G data will be explained as third
digital data.
[0046] Below, the configurations and functions of the components of
the liquid crystal display device 10 of the present embodiment will
be sequentially explained.
[0047] In the effective display portion 12, a plurality of pixels
including liquid crystal cells are arrayed in a matrix.
[0048] Then, in the effective display portion 12, data lines and
vertical scan lines driven by the horizontal drive circuits 13U and
13D and the vertical drive circuit 14 are laid in a matrix.
[0049] FIG. 5 is a diagram showing an example of the concrete
configuration of the effective display portion 12.
[0050] Here, for simplification of the drawing, a case of a pixel
array formed by three rows (n-1-th row to n+1-th row) and four
columns (m-2-th column to m+1-th column) is employed and shown as
an example.
[0051] In FIG. 4, in the display portion 12, vertical scan lines .
. . , 121n-1, 121n, 121n+1, . . . , and data lines . . . , 122m-2,
122m-1, 122m, 122m+1, . . . are laid in a matrix, and unit pixels
123 are arranged at intersecting portions of these.
[0052] Each unit pixel 123 is configured by a thin film transistor
TFT as the pixel transistor, a liquid crystal cell LC, and a
storage capacitor Cs. Here, the liquid crystal cell LC means a
capacity generated between a pixel electrode (one electrode) formed
by the thin film transistor TFT and a counter electrode (other
electrode) formed facing this.
[0053] Thin film transistors TFT are connected at their gate
electrodes to vertical scan lines . . . , 121n-1, 121n, 121n+1, . .
. and connected at their source electrodes to data lines . . . ,
122m-2, 122m-1, 122m, 122m+1,
[0054] The liquid crystal cell LC is connected at its pixel
electrode to a drain electrode of the thin film transistor TFT and
connected at its counter electrode to a common line 124. The
storage capacitor Cs is connected between the drain electrode of
the thin film transistor TFT and the common line 124.
[0055] The common line 124 is given a predetermined AC voltage as a
common voltage Vcom by a VCOM circuit 21 integrally formed with the
drive circuit etc. on the glass substrate 11.
[0056] Each of the first side ends of the vertical scan lines . . .
, 121n-1, 121n, 121n+1, . . . is connected to each output end of
the corresponding row of the vertical drive circuit 14 shown in
FIG. 3.
[0057] The vertical drive circuit 14 is configured so as to include
for example a shift register and performs a vertical scan by
sequentially generating vertical selection pulses in
synchronization with vertical transfer clocks VCK (not shown) and
giving these to vertical scan lines . . . , 121-1, 121n, 121n+1, .
. .
[0058] Further, in the display portion 12, for example, each of
first side ends of the data lines . . . , 122m-1, 122m+1, . . . ,
is connected to each output end of the corresponding column of the
first horizontal drive circuit 13U shown in FIG. 3, and each of the
other side ends is connected to each output end of the
corresponding column of the second horizontal drive circuit 13D
shown in FIG. 3.
[0059] The first horizontal drive circuit 13U stores three digital
data of R data, B data, and G data in sampling and latch circuits,
performs the processing for conversion to analog data three times
in one horizontal period (H), selects three data in a time division
manner within the horizontal period, and outputs the same to
corresponding data lines.
[0060] The first horizontal drive circuit 13U, along with
employment of this RGB selector scheme, transfers the R data and B
data latched in the first and second sampling and latch circuits to
the first latch circuit and further to the second latch circuit in
a time division manner, transfers the G data latched in the third
sampling and latch circuit during this time divisional transfer
processing of the R data and B data to the latch circuits to the
third latch circuit, selectively outputs the R, B, and G data
latched in the second latch circuit and third latch circuit in one
horizontal period and converts the same to analog data, and selects
three analog data in a time division manner in the horizontal
period and outputs the same to corresponding data lines.
[0061] Namely, in order to realize the RGB selector system, by
configuring the horizontal drive circuit 13U of the present
embodiment so that a first latch series for two digital data R and
B and a second latch series for one digital G data are arranged in
parallel and so that a digital-to-analog conversion circuit (DAC),
an analog buffer, and a line selector after the selector are
shared, a narrowing of the frame and lowering of the power
consumption will be achieved.
[0062] The second horizontal drive circuit 13D basically has the
same configuration as that of the first horizontal drive circuit
13U.
[0063] FIG. 6 is a block diagram showing an example of the
fundamental configuration of the first horizontal drive circuit 13U
and the second horizontal drive circuit 13D of the present
embodiment. In the following description, these will be explained
as "the horizontal drive circuit 13".
[0064] Note that this horizontal drive circuit exhibits a basic
configuration corresponding to three digital data. In actuality, a
plurality of same configurations are aligned in parallel.
[0065] The horizontal drive circuit 13, as shown in FIG. 6, has a
shift register (HSR) group 13HSR, a sampling and latch circuit
group 13SMPL, a latch output selection switch 13OSEL, a
digital-to-analog conversion circuit 13DAC, an analog buffer
13ABUF, and a line selector 13LSEL.
[0066] The shift register group 13HSR has a plurality of shift
registers (HSR) sequentially outputting shift pulses (sampling
pulses) to the sampling and latch circuit group 13SMPL from
transfer stages corresponding to columns in synchronization with
the horizontally transfer clocks HCK (not shown).
[0067] The sampling and latch circuit group 13SMPL has a first
sampling and latch circuit 131 sequentially sampling and latching
the R data as the first digital data, a second sampling and latch
circuit 132 sequentially sampling and latching the B data as the
second digital data, and latching the R data latched by the first
sampling and latch circuit 131 at the predetermined timing, a third
sampling and latch circuit 133 sequentially sampling and latching
the G data as the third digital data, a first latch circuit 134 for
serially transferring the digital data R or B data latched by the
second sampling and latch circuit 132, a second latch circuit 135
having a level shift function of converting the digital R or B data
latched by the first latch circuit 134 to a higher voltage
amplitude and latching the same, and a third latch circuit 136
having a level shift function of converting the digital G data
latched by the third sampling and latch circuit 133 to a higher
voltage amplitude and latching the same.
[0068] In the sampling and latch circuit group 13SMPL having such a
configuration, a first latch system 137 is formed by the first
sampling and latch circuit 131, second sampling and latch circuit
132, first latch circuit 134, and second latch circuit 135, and a
second latch system 138 is formed by the third sampling and latch
circuit 133 and third latch circuit 136.
[0069] In the present embodiment, the data input from the data
processing circuit 15 to the horizontal drive circuits 13U and 13D
are supplied at a level of a 0-3V (2.9V) system.
[0070] Then, by the level shift functions of the second and third
latch circuits 135 and 136 serving as output stages of the sampling
and latch circuit group 13SMPL, these are raised in level to for
example a -2.3V to 4.8V system.
[0071] The latch output selection switch 13OSEL selectively
switches outputs of the sampling and latch circuit group 13SMPL and
outputs the result to the digital-to-analog circuit 13DAC.
[0072] The digital-to-analog conversion circuit 13DAC performs
digital-to-analog conversion three times during one horizontal
period. Namely, the digital-to-analog conversion circuit 13DAC
converts three digital data R, B, and G to the analog data in one
horizontal period.
[0073] The analog buffer 13ABUF buffers the R, B, and G data
converted to analog signals at the digital-to-analog conversion
circuit 13DAC and outputs the same to the line selector 13LSEL.
[0074] The line selector 13LSEL selects three analog data R, B, and
G in one horizontal period and outputs the same to the
corresponding data lines DTL-R, DTL-B, and DTL-G.
[0075] Here, the operation in the horizontal drive circuit 13 will
be explained.
[0076] When the horizontal drive circuit 13 samples successive
image data, it stores these in the first, second, and third
sampling and latch circuits 131, 132, and 133.
[0077] When storage of all data of one line in the horizontal
direction in the first, second, and third sampling and latch
circuits 131 to 133 is completed, the data in the second sampling
and latch circuit 132 is transferred to the first latch circuit 134
in a horizontal direction blanking period and immediately
transferred to the second latch circuit 135 for storage.
[0078] Next, the data in the first sampling and latch circuit 131
is transferred to the second sampling and latch circuit 132 and
immediately transferred to the first latch circuit 134 for storage.
Further, in the same period, the data in the third sampling and
latch circuit 133 is transferred to the third latch circuit
136.
[0079] Then, the data of the next line in the horizontal direction
are stored in the first, second, and third sampling and latch
circuits 131, 132, and 133.
[0080] During the storage of the data of the next line in the
horizontal direction, the data stored in the second latch circuit
135 and third latch circuit 136 are output to the digital-to-analog
conversion circuit 13DAC by switching of the latch output selection
switch 13OSEL.
[0081] After that, the data stored in the first latch circuit 134
is transferred to the second latch circuit 135 and stored. That
data is output to the digital-to-analog conversion circuit 13DAC by
the switching of the latch output selection switch 13OSEL.
[0082] By this sampling and latch scheme, three digital data are
output to the digital-to-analog conversion circuit 13DAC, therefore
it becomes possible to realize higher definition and frame
narrowing.
[0083] Further, it is good from VT characteristic etc. of the
liquid crystal that the third digital data is not accompanied by
transfer work during the storage of the data of one line in the
horizontal direction and the data are written in an order of B
(Blue).fwdarw.G (Green).fwdarw.R (Red) in the case of the RGB
selector drive. Therefore, by selecting data of a color apt to give
the most influence upon the human eye, that is G data, this device
becomes strong against fluctuations in image quality.
[0084] The data processing circuit 15 has a level shifter 151
shifting levels of the parallel digital data R, G, and B input from
the outside from the 0-3V (2.9V) system to a 6V system, a
serial-to-parallel conversion circuit 152 converting the level
shifted R, G, and B data from the serial data to parallel data for
phase adjustment or lowering frequencies, and a down converter 153
down shifting the parallel data from the 6V system to the 0-3V
(2.9V) system, outputting odd number data (odd-data) to the
horizontal drive circuit 13U, and outputting even number data
(even-data) to the horizontal drive circuit 13D.
[0085] The power supply circuit 16 includes a DC-DC converter,
supplied with a liquid crystal voltage VDD1 (for example 2.9V) from
for example the outside, boosts up this voltage to an internal
panel voltage VDD2 of the double 6V system (for example 5.8V) in
synchronization with a master clock MCK and horizontal
synchronization signal Hsync supplied from the interface circuit
17, or based on correction clocks obtained by correcting clocks
having low (slow) frequencies and having a variation in oscillation
frequencies by a predetermined correction system by a built-in
oscillation circuit and the horizontal synchronization signal
Hsync, and supplies the same to circuits inside the panel.
[0086] Further, the power supply circuit 16 generates, as internal
panel voltages, VSS2 (for example -1.9V) and VSS3 (for example
-3.8V) as negative voltages and supplies the same to predetermined
circuits (interface circuit etc.) inside the panel.
[0087] The interface circuit 17 level shifts levels of the master
clock MCK, horizontal synchronization signal Hsync, and vertical
synchronization signal Vsync supplied from the outside up to a
panel internal logic level (for example VDD2 level), supplies the
master clock MCK, horizontal synchronization signal Hsync, and
vertical synchronization signal Vsync after the level shift to the
timing generator 18, and supplies the horizontal synchronization
signal Hsync to the power supply circuit 16.
[0088] The interface circuit 17 can be configured not to supply the
master clock MCK to the power supply circuit 16 in a case where the
power supply circuit 16 has a configuration performing the boosting
based on correction clocks obtained by correcting clocks of the
built-in oscillation circuit without using the master clock.
Alternatively, it is also possible to configure the device to keep
the supply line of the master clock MCK from the interface circuit
17 to the power supply circuit 16 as it is, but not to use the
master clock MCK for boosting on the power supply circuit 16
side.
[0089] The timing generator 18, in synchronization with the master
clock MCK, horizontal synchronization signal Hsync, and vertical
synchronization signal Vsync supplied by the interface circuit 17,
generates a horizontal start pulse HST and a horizontal clock pulse
HCK (HCKX) used as clocks of the horizontal drive circuits 13U and
13D and a vertical start pulse VST and a vertical clock VCK (VCKX)
used as clocks of the vertical drive circuit 14, supplies the
horizontal start pulse HST and horizontal clock pulse HCK (HCKX) to
the horizontal drive circuits 13U and 13D, and supplies the
vertical start pulse VST and vertical clock VCK (VCKX) to the
vertical drive circuit 14.
[0090] Next, the operation according to the above configuration
will be explained.
[0091] The parallel digital data input from the outside are
subjected to the parallel conversion for phase adjustment or
lowering the frequencies at the data processing circuit 15 on the
glass substrate 11, and the R data, B data, and G data are output
to the first and second horizontal drive circuits 13U and 13D.
[0092] In the first and second horizontal drive circuits 13U and
13D, the digital G data input from the data processing circuit 15
are sequentially sampled and latched for 1H at the third sampling
and latch circuit 133. After that, these are transferred to the
third latch circuit 136 in the horizontal blanking period.
[0093] Parallel to this, the R data and B data are separately
sampled for 1H and held in the first and second sampling and latch
circuits 131 and 132 and transferred to the first latch circuit 134
in the next horizontal blanking period.
[0094] When the storage of all data of one line in the horizontal
direction in the first, second, and third sampling and latch
circuits 131 to 133 is completed, the data in the second sampling
and latch circuit 132 is transferred to the first latch circuit 134
in the horizontal direction blanking period and immediately
transferred to the second latch circuit 135 and stored.
[0095] Next, the data in the first sampling and latch circuit 131
is transferred to the second sampling and latch circuit 132,
immediately transferred to the first latch circuit 134, and stored.
Further, in the same period, the data in the third sampling and
latch circuit 133 is transferred to the third latch circuit
136.
[0096] Then, the data of the next line in the horizontal direction
are stored in the first, second, and third sampling and latch
circuits 131, 132, and 133.
[0097] During the storage of the data of the next line in the
horizontal direction, the data stored in the second latch circuit
135 and third latch circuit 136 are output to the digital-to-analog
conversion circuit 13DAC by the switching of the latch output
selection switch 13OSEL.
[0098] After that, the data stored in the first latch circuit 134
is transferred to the second latch circuit 135 and stored. That
data is output to the digital-to-analog conversion circuit 13DAC by
the switching of the latch output selection switch 13OSEL.
[0099] In the next 1H period, the R, B, and G data converted to the
analog data at the digital-to-analog conversion circuit 13DAC are
held in the analog buffer 13ABUF, and the analog R, B, and G data
are selectively output to the corresponding data lines in a form
where the 1H period is divided to three.
[0100] Note that the processing of the G, R, and B can be realized
even when their orders are switched.
[0101] According to the present embodiment, the device has the
first latch system 137 cascade connecting the sampling and latch
circuits 131 and 132, first latch circuit 134, and second latch
circuit 135 for the first digital data (R) and the second digital
data (B) and sequentially transferring the data and the second
latch system 138 cascade connecting the sampling and latch circuit
133 and third latch circuit 136 for the third digital data and has
the common digital-to-analog (DA) conversion circuit 13DAC, analog
buffer circuit 13ABUF, and line selector 13LSEL selectively
outputting three analog data (R, B, G) to corresponding data lines
during one horizontal period (H), therefore the following effects
can be obtained.
[0102] By employing this configuration, the number of the DA
conversion circuits/analog buffer circuits which become necessary
is decreased compared with the existing system at the same dot
pitch, and it becomes possible to realize narrowing of the
frame.
[0103] Further, by configuring the data processing circuit from the
first and second digital data use and third digital data use
sampling and latch circuits, it becomes possible to realize higher
definition.
[0104] Namely, according to the present system, a three-line
selector system achieving higher definition and narrowing of the
frame, and the integral drive circuit type display device using
this can be realized on the insulating substrate.
[0105] Further, the number of circuits of the horizontal drive
circuits can be decreased, therefore a low power consuming
three-line selector system and an integral drive circuit type
display device using this can be realized.
[0106] Further, a three-line selector system which operates at a
high speed since it divides data to three and outputs the data to
the signal lines during one horizontal period, but is strong
against variations in the image quality and an integral drive
circuit type display device using this can be realized.
Second Embodiment
[0107] Next, more preferred configurations of the first and second
horizontal drive circuits in the integral drive circuit type
display device according to the present invention will be explained
as a second embodiment.
[0108] FIG. 7 is a circuit diagram showing a concrete configuration
of a first latch system of the horizontal drive circuit according
to the second embodiment. Further, FIG. 8 is a circuit diagram
showing a concrete configuration of a second latch system of the
horizontal drive circuit according to the second embodiment.
[0109] In FIG. 7, the first latch system 137 of FIG. 6 is indicated
by notation 200, the first sampling and latch circuit 131 is
indicated by notation 210, the second sampling and latch circuit
132 is indicated by notation 220, the first latch circuit 134 is
indicated by notation 230, and the second latch circuit 135 is
indicated by notation 240.
[0110] Further, in FIG. 8, the second latch system 138 of FIG. 6 is
indicated by notation 300, the third sampling and latch circuit 133
is indicated by notation 310, and the third latch circuit 136 is
indicated by notation 320.
[0111] The circuit of FIG. 7 is configured by the first sampling
and latch circuit 210 latching the first digital R data by a
sampling pulse SP from a not shown shift register, the second
sampling and latch circuit 220 latching the second digital B data
by the same sampling pulse SP, the first latch circuit 230
transferring the digital R data and B data all together after that,
and the second latch circuit 240 performing the level shift of the
transferred digital data.
[0112] The not shown shift register, first sampling and latch
circuit 210, second sampling and latch circuit 220, and first latch
circuit 230 perform the transfer and holding operation by the first
power supply voltage VDD1 (VSS) of the 0-3V (2.9V) system, and the
second latch circuit 240 performs the holding and data output
operations by a change of voltages to the second power supply
voltages VH1 and VL1 of for example a -12.3 to 5.8V system.
[0113] Note that, the R and B data use output circuit of the
sampling and latch circuit group is configured by the first latch
and second latch.
[0114] The first sampling and latch circuit 210 includes n-channel
transistors NT211 to NT218 and p-channel transistors PT211 to
PT214.
[0115] The transistor NT211 configures an input transfer gate 211
of the R data to the gate of which the sampling pulse SP is
supplied.
[0116] A latch 212 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT211 and
NT212 and the transistors PT212 and NT213. Further, an inverted
signal XSP of the sampling pulse is supplied to the gate of the
transistor NT214, whereby an equalizer circuit 213 of the latch 212
is configured.
[0117] An output buffer 214 formed by a CMOS inverter is configured
by the transistors PT213 and NT215.
[0118] An output buffer 215 formed by a CMOS inverter is configured
by the transistors PT214 and NT216.
[0119] Then, a signal Oe1 is supplied to the gate of the transistor
NT217, whereby an output transfer gate 216 to the second sampling
and latch circuit 220 of the output buffer 214 is configured, and
the signal Oe1 is supplied to the gate of the transistor NT218,
whereby an output transfer gate 217 to the second sampling and
latch circuit 220 of the output buffer 215 is configured,
[0120] The second sampling and latch circuit 220 includes n-channel
transistors NT221 to NT226 and p-channel transistors PT221 to
PT223.
[0121] The transistor NT221 configures an input transfer gate 221
of the B data to the gate of which the sampling pulse SP is
supplied.
[0122] A latch 222 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT221 and
NT222 and the transistors PT222 and NT223. Further, the inverted
signal XSP of the sampling pulse is supplied to the gate of the
transistor NT224, whereby an equalizer circuit 223 of the latch 222
is configured.
[0123] An output buffer 224 formed by a CMOS inverter is configured
by the transistors PT223 and NT225.
[0124] Then, a signal Oe2 is supplied to the gate of the transistor
NT226, whereby an output transfer gate 216 to the first latch
circuit 230 of the output buffer 224 is configured.
[0125] The first latch circuit 230 includes n-channel transistors
NT231 to NT235 and p-channel transistors PT231 to PT233.
[0126] A latch 231 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT231 and
NT231 and the transistors PT232 and NT232. Further, an inverted
signal XOe3 of a signal Oe3 is supplied to the gate of the
transistor NT233, whereby an equalizer circuit 232 of the latch 231
is configured.
[0127] An output buffer 233 formed by a CMOS inverter is configured
by the transistors PT233 and NT234.
[0128] Then, the signal Oe3 is supplied to the gate of the
transistor NT235, whereby an output transfer gate 234 to the second
latch circuit 240 of the output buffer 233 is configured.
[0129] The second latch circuit 240 includes n-channel transistors
NT241 to NT244 and p-channel transistors PT241 to PT244.
[0130] A latch 241 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT241 and
NT241 and the transistors PT242 and NT242. Further, a signal XOe4
is supplied to the gate of the transistor NT243 and a signal Oe4 is
supplied to the gate of the transistor PT243, whereby an equalizer
circuit 242 of the latch 241 is configured.
[0131] An output buffer 243 formed by a CMOS inverter is configured
by the transistors PT244 and NT244.
[0132] This second latch circuit 240 operates by the supply of
voltages VH1 and VL1 as the second power supply voltage system.
[0133] In the circuit of FIG. 7, when sampling successive image
data, the image data (R data or B data) existing in the first
sampling and latch circuit 210 are stored in a CMOS latch cell 212.
Simultaneously with that, image data (B data or R data) of the
second sampling and latch circuit 220 which is different from the
above data is stored in a CMOS latch cell 222.
[0134] When the storage of all data of one line in the horizontal
direction into the first sampling and latch circuit 210 and second
sampling and latch circuit 220 is completed, the data of the CMOS
latch cell 222 in the second sampling and latch circuit 220 is
transferred to the first latch circuit 230 in the horizontal
direction blanking period and immediately stored in the second
latch circuit 240. At this time, the CMOS latch 231 structure is
released so that the first latch circuit 230 does not hold the
data.
[0135] When the transfer of the data in the second sampling and
latch circuit 220 to the second latch circuit 230 ends, the data
stored in the first sampling and latch circuit 210 is transferred
to the second sampling and latch circuit 220 next and immediately
stored in the first latch circuit 230.
[0136] During the period where the data of the next line in the
horizontal direction is stored in the first sampling and latch
circuit 210 and second sampling and latch circuit 220, the first
data stored in the second latch circuit 240 is output to the
selection switch. When the transfer of the first data to the
selection switch ends, the second data stored in the first latch
circuit 230 is input to the selection switch.
[0137] Two digital data are operated by one sampling and latch
circuit according to this sampling and latch scheme, therefore
reduction of the Hdot pitch can be realized, which enables high
resolution.
[0138] The third sampling and latch circuit 310 includes n-channel
transistors NT311 to NT316 and p-channel transistors PT311 to
PT313.
[0139] The transistor NT311 configures an input transfer gate 311
of the G data to the gate of which the sampling pulse SP is
supplied.
[0140] A latch 312 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT311 and
NT312 and the transistors PT312 and NT313. Further, the inverted
signal XSP of the sampling pulse is supplied to the gate of the
transistor NT314, whereby an equalizer circuit 313 of the latch 312
is configured.
[0141] An output buffer 314 formed by a CMOS inverter is configured
by the transistors PT313 and NT315.
[0142] Then, a signal Oe5 is supplied to the gate of the transistor
NT316, whereby an output transfer gate 315 to the third latch
circuit 320 of the output buffer 314 is configured.
[0143] The third latch circuit 320 includes n-channel transistors
NT321 to NT324 and p-channel transistors PT321 to PT324.
[0144] A latch 321 is configured by cross connecting inputs and
outputs of CMOS inverters configured by the transistors PT321 and
NT321 and the transistors PT322 and NT322. Further, a signal XOe6
is supplied to the gate of the transistor NT323 and a signal Oe6 is
supplied to the gate of the transistor PT323, whereby an equalizer
circuit 322 of the latch 321 is configured.
[0145] An output buffer 323 formed by a CMOS inverter is configured
by the transistors PT324 and NT324.
[0146] This third latch circuit 320 operates by the supply of
voltages VH2 and VL2 as the second power supply voltage system.
[0147] In the circuit of FIG. 8, when sampling successive image
data, the image data (G data) are sampled to the third sampling and
latch circuit 310 and stored in a CMOS latch cell 312.
[0148] When the storage of the data of one line in the horizontal
direction into the third sampling and latch circuit 310 is
completed, the data of the CMOS latch cell 312 in the first
sampling and latch circuit 310 is transferred to the third latch
circuit 320 in the horizontal direction blanking period.
[0149] During the period where the data of the next line in the
horizontal direction is stored in the third sampling and latch
circuit 310, the data stored in the third latch circuit 320 is
output to the selection switch.
[0150] By this circuit configuration, the number of sampling and
latch circuits required for sampling data is decreased from the
existing system. This contributes to reduction of the Hdot pitch.
Further, the change from the existing type sampling and latch
circuit to the new sampling and latch circuit makes reduction of
power consumption possible.
[0151] Namely, in the existing system, the horizontal drive circuit
needs Hdot number.times.3 (RGB) sampling and latch circuits, DACs,
and analog buffers or needs Hdot number.times.2 sampling and latch
circuits, DACs, and analog buffers. Therefore, this became an
obstacle for realization of reduction of the pitch.
[0152] Contrary to this, in the present embodiment, three image
data are processed by one sampling and latch circuit group, latch
output selection switch, DA conversion circuit, analog buffer, and
3-selection switch. Therefore, when these are arranged above (or
below) the display area, one horizontal drive circuit may be
arranged for two Hdot pitches. At this time, another horizontal
drive circuit is arranged on an opposite side, therefore the higher
definition and narrower frame can be realized. Further, the number
of circuits can be decreased can be less than the existing
circuits, therefore it is possible to suppress the power
consumption.
[0153] FIG. 9 is a diagram showing the relationships of up/down
direction frame sizes and potential higher definition regions of
the existing system and the system of the present invention when
realizing the device of FIG. 3 and FIG. 4 by QVGA.
[0154] As seen from FIG. 9, in the system of the present invention,
in comparison with the existing system, a three-line selector
system achieving higher definition and narrower frame and an
integral drive circuit type display device using this can be
realized on an insulating substrate.
Third Embodiment
[0155] FIG. 10 and FIG. 11 are diagrams schematically showing an
example of the configuration of an integral drive circuit type
display device according to a third embodiment of the present
invention, in which FIG. 10 is a diagram showing a layout
configuration of the integral drive circuit type display device
according to the present third embodiment, and FIG. 11 is a system
block diagram showing the circuit functions of the integral drive
circuit type display device according to the third embodiment.
[0156] The difference of the third embodiment from the first and
second embodiments explained above resides in that the integral
drive circuit type display device is realized by arranging a
horizontal drive circuit on only one side.
[0157] When employing this scheme, the pitch of the number of Hdots
which can be arranged becomes halved. Therefore, higher definition
can not be achieved in comparison with FIG. 3 and FIG. 4, but it is
possible to realize narrowing of the area of the side where a
horizontal drive circuit is not arranged.
[0158] Note that, in the above embodiments, an explanation was
given by taking as an example the case where the present invention
was applied to an active matrix type liquid crystal display device,
but the present invention is not limited to this. The present
invention can be applied to an EL display device or other active
matrix type display device using electroluminescence (EL) elements
as electro-optic elements of the pixels in the same way as
well.
[0159] Further, the active matrix type display device represented
by the active matrix type liquid crystal display device according
to the above embodiments is preferred particularly when used as the
display portions of mobile phones, PDAs, or other mobile terminal
devices in which reduced size and greater compactness of the device
body are advanced in addition to application to displays of
personal computers, word processors, and other OA apparatuses,
television receivers, etc.
[0160] FIG. 12 is a view of the appearance schematically showing
the configuration of a mobile terminal device to which the present
invention is applied, for example, a mobile phone.
[0161] A mobile phone 400 according to the present example is
configured by a speaker portion 420, a display portion 430, an
operation portion 440, and a microphone portion 450 arranged on a
front surface side of a device case 410 in order from an upper
portion side.
[0162] In a mobile phone having such a configuration, for example a
liquid crystal display device is used for the display portion 430.
As this liquid crystal display device, used as this liquid crystal
display device is the active matrix type liquid crystal display
device according to the previously explained embodiment.
[0163] In this way, in the mobile phone or other mobile terminal
device, by using the active matrix type liquid crystal display
device according to the previously explained embodiment as the
display portion 430, in circuits mounted on this liquid crystal
display device, pitch narrowing is possible, frame narrowing can be
realized, and reduction of the power consumption of the display
device can be achieved and accordingly reduction of the power
consumption of the terminal device becomes possible.
INDUSTRIAL APPLICABILITY
[0164] In the display device and electronic device of the present
invention, pitch narrowing is possible, frame narrowing can be
realized, and further lowering of power consumption is possible.
Therefore, in addition to the use as displays of personal
computers, word processors, and other OA apparatuses, television
receivers, etc., these can be applied particularly as the display
portions of mobile phones, PDAs, or other mobile terminal devices
in which reduction of size and greater compactness of the device
body is advanced.
* * * * *